It is of great significance to implement the source control of FGD for the whole process of ultra-low emission transformation in the iron and steel industry，at present. The difficulty of desulfurization of blast furnace gas is the removal of carbonyl sulfur(COS). Aiming at the emission characteristics of blast furnace gas with frequent temperature fluctuations，high pressure and complex components，alumina catalyst was used to catalyze and hydrolyze COS，and the effects of temperature，chloride ion，dust and oxygen on the conversion rate of carbonyl sulfur were investigated. The influence degree and mechanism of various factors on COS hydrolysis were analyzed. The results indicate that the temperature has the most significant effect on the efficiency of COS hydrolysis. When the temperature is increased from 50 ℃ to 150 ℃，the hydrolysis efficiency increases from 49% to 90%. The higher temperature is conducive to the occurrence of COS hydrolysis reaction. Chloride ion reduces the specific surface area of the catalyst by 20.1%，and the pore volume by 40.0%. The catalyst deactivation caused by chloride ion comes from two aspects，including the reduction of alkaline center on the surface of hydrolysis catalyst，the blockage of catalyst channels and the covering of some active sites. Chloride ion has the most significant inactivation effect. The nano dust in blast furnace gas has a blocking effect on the catalyst pore，reduces the specific surface area of the catalyst by 43.5% and the pore volume by 60.0%. The hydrolysis efficiency decreases significantly with the accumulation of dust. When the oxygen concentration is 0.5%，the hydrolysis efficiency decreases from 85% to 82% with the extension of reaction time and there is no significant decline. Still，when the oxygen concentration increases to 1%，the hydrolysis efficiency decreases from 85% to 66%，the inhibition effect of sulfur deposition is obvious when the oxygen concentration increases. Anti-chlorine，dust resistance and oxygen resistance are the key factors of hydrolysis catalyst. Pre-removal of multiple components in industry can be adopted before hydrolysis to reduce the impact of blast furnace gas impurities on COS hydrolysis efficiency.